Customized Surgical Guide for Acetabular Cup Placement
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Solution Overview
Problem
Current prosthetic systems for joint replacement, particularly acetabular cups, face challenges in accurate sizing and placement due to sub-hemispherical shapes and reduced surface contact, leading to difficulties in reaming and bone ingrowth, and generic designs that do not conform to individual patient anatomy, complicating surgical procedures for less experienced surgeons.
Innovation Solution
A method for designing and manufacturing customized surgical guides using computed tomography data to create three-dimensional bone surface images, which are then used to generate control data for fabricating guides that conform to the patient's anatomy, ensuring accurate placement and orientation of prosthetic components without interfering with the surgical site.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If press fitted acetabular cups with flared rim or frusto-conically shaped annular rim portion are used to increase retaining forces, then retention forces at the rim portion are improved, but surface contact and retention forces at other portions of the outer shell are reduced
Solution Approach 1:
The surgical guide incorporates localized engagement features (flanges with bone-contacting surfaces) that provide stable positioning at specific anatomical locations without interfering with the overall cup geometry. This allows the cup itself to maintain its optimized dual-geometry or flared rim design for maximum bone ingrowth and retention, while the guide's localized features ensure accurate positioning during implantation.
Solution Approach 2:
The surgical guide acts as an intermediary tool that temporarily interfaces with the bone structure to establish precise orientation and positioning. The guide's flanges engage with specific bone surfaces to create a stable reference framework, allowing the surgeon to accurately position the cup without the guide interfering with the cup's optimal geometric design for bone ingrowth.
2Ease of manufacture
If sub-hemispherical acetabular cups are used, then implantation without cement is enabled, but difficulty in reaming properly sized cavity and accurate depth estimation arise
Solution Approach 1:
The surgical guide is designed with pre-configured depth indicators and engagement features that establish the correct reaming depth before the actual reaming process begins. The guide's flanges are positioned to engage specific bone surfaces that define the optimal reaming depth, eliminating the need for the surgeon to estimate depth during the procedure.
Solution Approach 2:
The patent replaces the traditional mechanical estimation method (surgeon visually estimating reaming depth) with a structured reference system based on anatomical landmarks. The guide translates complex three-dimensional anatomical relationships into simple two-dimensional reference surfaces that directly indicate the correct reaming depth, replacing subjective mechanical judgment with objective anatomical referencing.
3Adaptability or versatility
If generic surgical guides are used, then standardization is achieved, but accurate conformance to individual patient anatomy is compromised
Solution Approach 1:
The surgical guide incorporates localized customization features (flange shapes, bone-contacting surfaces, and engagement geometries) that are specifically adapted to each patient's unique anatomy based on preoperative imaging. These localized features provide precise anatomical conformance while the overall guide structure maintains standardized components for consistent performance and ease of manufacture.
Solution Approach 2:
The guide is divided into standardized components (main body, alignment features) and customized components (flanges, bone-contacting surfaces). This segmentation allows the standardized portions to be manufactured efficiently using conventional processes, while the customized portions are tailored to each patient's anatomy through CAD/CAM techniques based on their specific CT or MRI data.
4Manufacturing precision
If customized surgical guides are manufactured using traditional methods, then anatomical precision is improved, but manufacturing complexity and time increase
Solution Approach 1:
The patent replaces complex traditional manufacturing processes (manual machining, custom tooling, multiple assembly steps) with automated CAD/CAM and additive manufacturing technologies. The customized guide geometry is directly fabricated from digital models derived from patient imaging data, eliminating the need for complex mechanical manufacturing processes while maintaining high anatomical precision.
Solution Approach 2:
The manufacturing approach transitions from mechanical subtraction (machining) to additive fabrication (3D printing). This parameter change in the manufacturing process allows complex customized geometries to be produced as single integrated components rather than assembled from multiple machined parts, reducing manufacturing complexity while maintaining or improving anatomical conformance precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise and efficient placement of prosthetic components, reducing the risk of bone fracture and improving bone ingrowth, while allowing surgeons to maintain clear access and visibility during procedures, thus enhancing the accuracy and speed of joint replacement surgeries.
Implementation Method 1
controlling a laser with the generated control data to selectively crystallize a resin to form a surgical guide that corresponds to the surgical guide image
Data Source
AI summary
A method and system may be used to design and control the manufacture of a surgical guide for implanting a prosthetic component. The system includes a bone surface image generator, a surgical guide image generator, and a surgical guide image converter. The bone surface image generator receives three dimensional bone anatomical data for a patient's bone and generates a bone surface image. The surgical guide image generator generates a surgical guide image from the bone surface image and an image of a prosthesis imposed on the bone surface image. The supporting structure of the generated surgical guide image conforms to the surface features of the three dimensional bone surface image. The surgical guide image is converted by surgical guide image converter into control data for operating a machine to form a surgical guide that corresponds to the surgical guide image.